This disclosure relates to fasteners, such as screws and bolts, in general, and in particular, to composite fasteners that comprise two or more materials, including more than one type of reinforcing fiber, as well as methods for manufacturing such fasteners.
Conventional fasteners include high-strength but relatively heavy metallic fasteners, such as conventional threaded screws and bolts made of a variety of high-strength metals and alloys amenable to heat treatment, and relatively light but low-strength polymeric fasteners. The problem with the former is that they result in a high-density “overdesign,” whereas, the latter lack sufficient strength to be useful in applications requiring relatively high-strength, low creep fasteners, e.g., the airframes of modern jetliners, including aircraft having composite components.
Accordingly, there is a long felt but as yet unsatisfied need in the aircraft industry for fasteners that combine the high-strength advantage of metallic fasteners with the low weight advantage of polymer based composite fasteners, and methods for manufacturing them reliably and inexpensively. Such fasteners would provide for the low-mass fastening of two different substrates, and afford a substantial reduction in the weight of the resulting structures, e.g., aircraft structures.